1. Field of the Invention
The present invention relates to patient interface devices for transporting a gas to and/or from an airway of a patient, and in particular, to a patient interface device having a shaped headgear component with an inflatable bladder assembly.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle or varies with the condition of the patient (e.g., snoring, apneas, hyponeas), to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device including a patient sealing assembly, such as but not limited to, a mask component on the face of a patient. The mask component may be, without limitation, a nasal mask that covers the patient's nose, a nasal cushion having nasal prongs that are received within the patient's nares, a nasal/oral mask that covers the patient's nose and mouth, or a full face mask that covers the patient's face. The patient interface device interfaces the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Typical designs for the mask component of a patient interface device include a faceplate or shell having a cushion or seal attached thereto which seals around the nose and in the case of a nasal/oral interface, also around the mouth of the patient. The mask is typically strapped to the head of the patient using a headgear assembly comprised of a number of non-elastic straps connected to the faceplate. The straps may be adjustable, so that the headgear assembly may be tightened or loosened to adjust the fit of the headgear assembly and mask. Alternatively, the headgear assembly may be made of, or include, elastic strap members. Such elastic members may also have an adjustable length.
Because such patient interface devices are typically worn for an extended period of time, it is important for the headgear component to maintain the mask component of the device in a tight enough seal against the patient's face without causing discomfort. That is, if the straps are adjusted so as to be overly tight, the headgear assembly produces uncomfortable pressure on portions of the patient's head (possibly resulting in red mark formation on the skin). However, if the headgear assembly is loosened, the mask may not remain sealed against the patient's face.